1. Field of the Invention
The present invention relates to a dual-standby portable terminal capable of using heterogeneous networks. More particularly, the present invention relates to a dual-standby portable terminal and a method for connecting an audio path thereof, which does not utilize switching device to enter a slave Subscriber Identification Module (SIM) mode and does not require a tuning process.
2. Description of the Related Art
As the use of portable terminals increases, multifunctional portable terminals are being developed. Recently, multi-mode portable terminals capable of accessing two or more communication networks are being marketed.
The use of a single-mode portable terminal supporting one communication network enables communication only in the service area of a compatible communication network. However, the use of the multi-mode portable terminal enables communication in the service areas of two or more compatible communication networks. For example, the use of a dual-mode portable terminal supporting a Code Division Multiple Access (CDMA) network and a Global System for Mobile communication (GSM) network enables communication in both the service area of the CDMA network and the service area of the GSM network. Therefore, dual-mode portable terminals are more useful than single-mode portable terminals.
The dual-mode portable terminal switches between communication networks through a menu operation by entering an idle mode after completing a booting operation, thus requiring complex control and consuming much time.
Dual-standby portable terminals have been proposed to address the above problem. Unlike the dual-mode portable terminal, the dual-standby portable terminal can support the CDMA network and the GSM network simultaneously. The dual-standby portable terminal requests/receives a preamble and/or a pilot channel signal from the CDMA network and the GSM network periodically, even in an idle mode, to measure channel conditions (e.g., Received Signal Strength Indicator (RSSI), Carrier to Interference-plus-Noise Ratio (CINR), and Quality of Service (QoS)), thus supporting the two networks simultaneously.
The dual-standby portable terminal has two SIM modes that operate selectively in different frequency bands. For example, in a master SIM mode, a slave SIM switches into a sleep state. That is, the components of the portable terminal are controlled by a control unit activated in the master SIM mode. However, in a slave SIM mode, a master SIM is activated to control the components (e.g., a switching unit and a Bluetooth device) of the portable terminal.
In the slave SIM mode, received voice data undergo audio parameter tuning and are switched by a switching device to be connected to an audio path in the master SIM mode.
However, the additional switching device increases the size of the portable terminal, and the complex audio parameter tuning operation delays product development.